Ureaplasma

U.re.a.plas'ma. N.L. fem. n. urea urea; Gr. neut. n. plasma anything formed or moulded, image, figure; N.L. neut. n. Ureaplasma urea form. Tenericutes / Mollicutes / Mycoplasmatales / Mycoplasmataceae / Ureaplasma. Bacteria in the genus Ureaplasma, pleomorphic, small (100->800 nm in diameter) primarily coccoid cells, devoid of a cell wall , surrounded by a trilaminar-membrane structure. Coccobacillary and filamentous forms also occur. These bacteria form exceptionally tiny (< 0.2 mm) colonies on solid media. Like the closely-related genus Mycoplasma, ureaplasmas have small (0.75 – 1. 01 Mb) A+T-rich genomes, use the codon UGA to encode tryptophan, and are nutritionally fastidious. Unlike mycoplasmas they hydrolyze urea rather than glucose or arginine for ATP synthesis. DNA–DNA hybridizations, serotyping of phase-variable surface-exposed lipoproteins (the multiple - banded antigen [MBA]), PCR and sequencing of the multiple–banded antigen gene (mba), 16S rRNA and urease genes have defined the species and serovars for this genus. In nature all species are commensals and/or opportunistic pathogens of vertebrate hosts. Based on the most recent comparative genome analyses, a consensus is emerging that strains associated with humans, the species Ureaplasma urealyticum and Ureaplasma parvum, undergo extensive horizontal gene transfer and may exist collectively as quasi-species rather than as stable serovars in their native environment..